Fuses are being incorporated with increasing frequency to improve manufacturing yield or to design application specific integrated circuits. Fuses are selectively blown, or programmed, to allow redundant components to replace defective components in the circuit, or to adapt an integrated circuit to perform a specific operation. To program the integrated circuit for a specific task, fuses embedded in the circuit are either kept intact to maintain a conduction path, or blown to create an open circuit, according to a predefined design.
Large numbers of fuses are presently used to implement increasingly sophisticated integrated circuit programming. The implementation of a particular design can require the blowing of thousands of fuses on an integrated circuit die. To obtain high numbers of properly programmed devices, the fuses must be blown with extremely high yield (e.g., 99.99%). Continuing refinements in the materials and process used to fabricate integrated circuits with increasingly smaller and faster transistor components present constant new challenges to fuse designs.
For instance, fuses are typically constructed of the same materials as used to fabricate transistors or other active or passive device components. Changes in the type of polysilicon or metal silicide, or in their thicknesses, doping or other parameters used for transistor fabrication, and hence fuse device fabrication, can dramatically decrease one's ability to blow fuses in high yields. In some cases a high blow yield can be restored by changing the amount or timing of power applied to the fuse. In other cases a different fuse structure must be designed. Both of these measures increase manufacturing costs and delay integrated circuit production.
Accordingly, what is needed in the art is a semiconductor device fuse that can be reliably programmed independent of changes made in transistor manufacturing materials and processes.